After
finalising some of the steel bracing the firebox arches have been
constructed. The bricks below the arches are all loose to allow
for removal to clean the ashpits between firings. Those marked 1
and 2, and the bricks immediately behind them, are not standard
sized bricks. These are the bricks immediately above the secondary
air holes, and immediately below the front hobs.If necessary the
secondary air holes can be reduced in size so a normal brick will
span them comfortably. When this kiln is being stoked at full
speed each secondary air hole is opened to only 3 inches by 4.5
inches. Any extra opening is used for raking coals away from the
throat arches.